Online ads that target users' behaviour will become the issue of a debate in the US Congress in the coming weeks. Democratic representative Rick Boucher and other congressmen plan to table a bill in the House of Representatives.

The battle between US marketers and consumer advocates has heated up after an independent study revealed that two thirds of Americans reject being tracked online by advertisers. Some 66% do not want marketers to tailor advertisements to their interests. Meanwhile, 69% think that there should be a law that gives people the right to know everything a website knows about them, a survey by researchers at the University of Pennsylvania and the University of California, Berkeley, revealed.

Targeted advertising is different from contextual advertising, which does not involve the maintenance or storage of information about an individual beyond their current online session. Behavioural targeting is the practice of collecting and compiling data from and about an individual's activity.

The issue of behavioural tracking provoked controversy in the UK when profiling firm Phorm conducted trials of its technology with BT. The debate led the UK Department of Business, Innovation and Skills to endorse its use only under tight conditions. The Office of Fair Trading is now conducting a study looking at the current consumer law surrounding advertising and pricing.

Behavioural advertising has been seen as a potentially lucrative revenue generator. In order to better target ads and products, companies are trying to make use of web interactivity and learn about users' browsing habits and personal information.

After the controversy with Phorm, BT put its contract on ice and stopped all immediate plans to deploy the targeting product. Other UK companies cancelled their contracts as well, or put them on hold. Phorm posted a $15m (£9m) operating loss in the six months to the end of June, down from $25.6m in the same period last year.

Marketers have argued that advertising supports free online content. In a bid to prevent regulation, big advertising trade groups in the US proposed in July measures such as clear notices to make consumers when they were being tracked. They are hoping to fend off regulation, and would rather regulate themselves. However, the new head of the Bureau of Consumer Protection at the the Federal Trade Commission, David C Vladeck, has suggested an "opting-in" system that would requiring sites collecting personal data to get consumers' consent. Marketers say such a tactic would be disastrous.

What do you think: Should there be a law against behavioural tracking or is a self-regulation enough? Is targeted advertising the flipside of a free web? What is your opinion about behavioural advertising?